Similar experience here with Benelli R1 Pro .30-06; mine appears to be failure to eject which increases in frequency after my second box of ammo at the range. I typically use match grade only and clean thoroughly immediately upon returning home, following manual instructions. My personal conclusion (which may or may not be accurate) is that this is inherent due to the nature of the firearm, as I believe it’s intended purpose leans toward hunting rather than target shooting- just a few rounds down range per year may be all it takes for some to fill their freezer without expending enough ammo to encounter a mounting failure issue. Rather, after just a few boxes of ammo at the gun range, I’m only getting started. Somewhat disappointed, I’m now in the market for a Springfield .308.